1. Field of the Invention
The present invention relates to a semiconductor ingot machining method.
2. Description of the Prior Art
FIG. 7(A)-(D) shows the prior art grinding and cutting method for semiconductor ingots 10.
FIG. 7(A) First, the semiconductor ingot 10 is mounted in an outer diameter saw slicing machine with a blade thickness of approximately 2500 .mu.m. The two ends, i.e. the head portion 12 and the tail portion 13 are separated from the cylindrical body portion 11 of the semiconductor ingot 10 and a sample 14 is cut off for lifetime measurement from the tail portion 13 end.
FIG. 7(B) Next, the cylindrical body portion 11 is mounted in an inner diameter saw slicing machine with a blade thickness of approximately 400 .mu.m and wafer samples 21, 22, 23 and 24 are cut off from both ends and the middle section of the cylindrical body portion 11 for crystal property inspection. With this, the block 25 is formed between the wafer samples 22 and 24, and the block 26 is formed between the wafer samples 23 and 24.
FIG. 7(C) The block 25 is mounted in a grinding device equipped with an azimuth reference positioning device that irradiates the block 25 with x-rays while rotating it around its axis to determine the azimuth reference position based upon the peak intensity of the diffracted rays.
FIG. 7(D) A grindstone is pressed down on the circumference surface of the block 25 while it is being rotated. The block 25A is obtained by cylindrically grinding the block 25 by moving the grindstone parallel to the axis of rotation of the block 25.
FIG. 7(E) The block 25B is fixed at an appropriate angular position in relation to the grinding device and by moving the grindstone and grinding the block 25B parallel to the axis of the block 25B, an orientation flat OF or a notch not shown is formed at the azimuth reference position which has been determined during the above step C.
The steps in FIGS. 7(C) to 7(D) above are performed similarly for the block 26.
Since each of the blocks 25 and 26 must be aligned and mounted in the grinding device, the azimuth reference position must be determined, and cylindrical grinding and surface grinding or notch grinding must be performed for each block, the entire process becomes complex. Therefore, full automation and systematization of such a procedure involves complicated equipment and facilities. Also, as cutting must be performed by placing the blade on the inclined faces at both ends of the semiconductor ingot 10 in the step in FIG. 7(A), it is not possible to use an inner diameter saw slicing machine with its higher cutting speed and thinner blade for if used, damage to the blade is likely to occur at the time of cutting, greatly reducing the life of the blade. As a result, different cutting devices must be used for the step in FIG. 7(A) and the step in FIG. 7(B). Also, since the ingot must be aligned for mounting each time, the whole process becomes even more complex and makes automation of the system even more complicated.